This work illustrates how the Analysis of Controlled Deformation in Rocks and Soils (ADECO-RS) is used in the design and the construction of tunnels. This is a very new and effective way of tunnel construction. The ADECO-RS approach makes a clear distinction between the design and the construction stages and allows reliable forecasts of construction times and costs to be made. It uses the advance core (the core of ground ahead of the face) as a structural tool for the long and short term stabilisation of tunnels, after its rigidity has first been regulated using conservation techniques.